back to article CERN boffins re-running neutrino speed test

In the wake of September’s surprising experimental results that suggested the observation of faster-than-light neutrinos, CERN has announced that it has been re-running the experiment over recent days. Since the pre-publication release of its original dataset, CERN’s data has been raked over by physicists, scientists, computer …

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  1. Richard French
    Boffin

    Can anyone explain why the experiment doesn't use a fibre optic loop so that the neutrinos can be received by the same facility as send them out in the first place. This would reduce the complexity of the experiment removing time anomalies (or have I missed something in my naive knowledge of physics).

    1. Wize

      Because it neutrinos, not photons.

      I shouldn't take the piss tho. Its a good idea. But I don't think they have neutrino compatable reflectors.

    2. cloudgazer

      Simple answer, because you can't constrain neutrinos to a fibre optic cable, why would you be able to? Fibre optic isn't magic - it only works on photons, and only photons of certain energies at that.

    3. Anonymous Coward 99

      Neutrino Physics 101

      Because neutrinos hardly interact with matter, you can't steer them once they have been produced. The only way the experiment works is by putting the detector in line with the beam that is being produced. Then you have to work out which neutrinos MAY have come from the source (since the universe is filled with background, ....)

    4. Mike 140
      Alien

      Sorry, but yes, you have. Neutrinos aren't affected by a wave guide such as a fibre optic cable. They stop for nothing and nobody. Their path is a geodesic. With only occasional exceptions they pass through matter as though it doesn't exist.

    5. tyo.

      You can't send neutrinos through a fiber because they won't reflect on its walls. Neutrinos practically don't interact with matter, they go right through it.

    6. Yes Me Silver badge

      Loop?

      Can't be done. Neutrinos travel through ordinary matter such as glass without taking much notice of it; they don't obediently follow along a fibre like photons do. Most of the neutrinos that make it from CERN to Gran Sasso aren't detected, they just continue on their way; just a very few of them interact with the detector material and get recorded.

      It's quite different from the original Michelson-Morley experiment that led Einstein to figure out relativity, where the photons were indeed reflected back.

    7. Michael Chester
      Boffin

      Neutrinos != light

      They would just pass straight through the fiber optic cable, and there's no good way of directing them which would allow you to send them in a circle (even the detectors are inefficient, since they interact so rarely with anything)

    8. John H Woods Silver badge
      Happy

      Yes...

      ... neutrinos won't go round a fibre optic loop. In fact they pass through pretty much everything, which is why creating a neutrino detector is such hard work.

    9. Robert E A Harvey

      I don't think you can persuade neutrinos to go round corners.

    10. Anonymous Coward 99

      Neutrino Physics 101

      Because Neutrinos hardly interact with normal matter, they cannot be steered, you have to put the detector in line with the source.

    11. Steen Hive

      Because neutrinos could pass through the walls of your 'fibre-optic' cable (and maybe right through the middle of every planet in the solar system as well) without even breaking a sweat.

    12. StevieB
      Stop

      Neutrinos are not photons.

      They act in ways different to light. The ones causing all the problems have been fired through 730km of rock, the chances of them following an optical fibre are, I would suggest, slim to none.

    13. Anonymous Coward
      Anonymous Coward

      The neutrinos are not being sent along a conduit, they are literally passing through the Earth to the detector, such is their nature. This site has a good explanation http://www.wired.com/geekdad/2011/09/neutrinos-and-the-speed-of-light-a-primer-on-the-cern-study/

    14. John G Imrie

      Youve missed something

      Nutrinos don't flow down a fiber optic cable the way light does. The problem with nutrinos is that they are so small the pass through allmost everything. Occasionally, where occasionally is a verry small number, one hits a sub atomic particle and can be detected.

    15. Sorry that handle is already taken. Silver badge

      Neutrinos care not for earthly possessions

      Neutrinos tend not to interact with matter, and anyway they're not photons so optical fibres would be unlikely to help even if they weren't so weakly interacting.

      To give an idea of how weakly interacting there are, the solar neutrino flux at the distance of earth's orbit from the sun is on the order of 10^14/m²s, and it takes gigantic detectors built in deep underground caverns containing tens of thousands of tonnes of water to pick up even a handful of them each year.

    16. wtf is a handle
      WTF?

      ET

      neutrinos pass through nearly any matter. Just looked it up and said even passes through planets, wtf

    17. Graham Dawson Silver badge

      Neutrinos only interact very weakly with matter and wouldn't follow an optical fibre.

    18. Martin Gregorie

      Because a neutrino beam can't be bent.

      Photons can be made to follow an optical fibre if the angle they make with the sides of the fibre is low enough for them to all be reflected back into the cable.

      However, neutrinos are particles that barely interact with other particles enough to be detected, which is why they can travel 732 km through solid rock. The chances of reliably deflecting such a beam in a circle are approximately zero. Similarly, they carry no electric charge so magnets won't deflect them either.

      To show how unreactive neutrinos are, Its been calculated that a neutrino beam can penetrate a lightyear of solid lead without loosing more than a few percent of its brightness and they can whistle through the sun almost without noticing that it was there.

      So, as collisions don't deflect them, they can't be reflected by anything, and magnets or electric fields don't affect them, you have no choice except to design the experiment around measuring a straight beam on neutrinos.

    19. Heironymous Coward
      Mushroom

      flogging a dead horse

      18 responses and counting, all with minor variations on the theme "neutrinos pass thru anything and are hard to detect", without any non-topical interruptions - got to be an El Reg record. Sorry to break the chain, guys :-)

    20. oldredlion
      Headmaster

      Has any one said neutrinos won't follow a loop yet?

    21. Cirret
      Headmaster

      Neutrinos are not photons. Neutrinos pass through matter almost as if it doesn't exist, so guiding them with optic fibre or anything else is a non-starter. I don't see why you think this would have simplified the experiment.

  2. Chris Haynes
    Coat

    A new dataset is expected by the end of November

    November?! I thought these things were moving faster than the speed of light?

    1. Steen Hive
      Joke

      November 30th, 1492

    2. Anomalous Cowturd
      Happy

      Bring it on...

      This is ALL fantastic stuff.

      The more accuracy, the better.

      Physics. The FULL understanding of which is what EVERYTHING is made of...

      Chemistry...

      Biology...

      It's all physics really...

      Possibly...

      Oh, and philosophy... :o)

      1. Allan George Dyer
        Boffin

        In the same way that...

        all [electronic] computing is toggling voltage levels. Just because you know the complete CPU instruction set, it doesn't mean you understand an XML schema or machine vision. A list of fundamental particles doesn't tell you about the elegance of the extended phenotype of a caddisfly larvae.

        Still, fantastic stuff about the bottom layer.

      2. Anonymous Coward
        Anonymous Coward

        Re: Bring it on

        "It's all physics really... Possibly..."

        Possibly not: http://xkcd.com/435/

      3. commonsense

        Actually...

        It's the best guess at an explanation of the things that we observert are made of.

    3. John 62
      Big Brother

      Movember

      They're going to measure how neutrinos will be affected by the moustaches being grown.

  3. NoSh*tSherlock!
    Boffin

    To Richard French

    Neutrinos are seriously hard to direct - from Cern they simply aimed directly at Grand Sasso through the earth - and they went through without a problem - further reading will tell you they are so good at slipping through stuff they receiver at Grand Sasso is solid lead and only records an occasional impact,

    So it is much like light going throuh space on a tiny scale - as far as a neutrino is concerned the occasional atom nucleus is so far from the next that a collision is very rare. Furthermore a neutrino does not carry any charge (AFAIK - correct me if I am wrong) so it does not easily get diverted by electrons or protons.

    If you sent it down a fibre optic it would simply go straight out at the first bend.

  4. Robert E A Harvey

    Igor!

    Igor! The Swit...

    Oh, you have already, already.

    1. Michael H.F. Wilkinson Silver badge
      Coat

      Yeth, marther!!

  5. Unicornpiss
    Pint

    @Richard French

    Not sure what you mean by a fibre optic loop. Neutrinos are not photons, and wouldn't be carried by a fibre-optic loop. They would pass through it completely, the same as they do through the entire planet. There is nothing known that can reflect them either. Using fibre optics wouldn't even work for a speed test with light, as the velocity of the photons would be changed by the fibre optic medium I believe, complicating the calculations.

  6. Richard French
    FAIL

    Enough already ....

    I didn't know HOW naive I was .... thanks for all the replies - I did have the whole thing A about T

    1. frank ly
      Happy

      And more.....

      It's A about F, or A over T. (It's your day for corrections isn't it?)

    2. Dan 10

      @Richard French

      Think yourself lucky - I asked more or less the same thing on a previous related article, but received a single thumbs down and no explanations!

  7. Anonymous Coward
    FAIL

    I Say Measurement Error

    Very much like "Cold Fusion" and all the perpetual energy generators out there.

  8. Anonymous Coward
    Anonymous Coward

    What about the *other* part of Richard's question?

    Ok, so we know that neutrinos won't follow a loop, but even if they could you would have another problem. In order to get any kind of accurate measurement you would need to have a decent sized loop*. As soon as you have a decent sized loop all the other problems related to a moving** frame of reference come back into play and you would have to try to compensate for the effects around the whole loop***.

    * A small loop would have the problem of "how many times has that neutrino been around?

    ** Earth revolving and orbitting.

    *** Which unfortunately are unlikely to add up to a net zero.

  9. Long John Brass
    Alert

    Igor we need more Igor's

    If CERN doesn't have an Igor on staff and a big red switch or lever I'm going to me very dissapointed.

    Lets face it, these guys are doing mad^H^H^H MAD science.

    Wild haired white-coated boffins are one thing

    But if you don't have an Igor or two, you just ain't doing it right :)

  10. Anonymous Coward
    Anonymous Coward

    This is old news

    Announced 3 days ago in many other places. El Reg is running behind. Not the first time btw.

    1. ~mico
      Trollface

      The delay in publication was caused by time dilation in the vicinity of superluminal neutrino beam.

    2. Heironymous Coward
      WTF?

      Yeah..

      It's like they get weekend off or something... WTF??

    3. John G Imrie

      No No No

      Ell Reg is on Standard Relativistic Time, every one else reporting this is on Neutrino Time.

      That's why the clocks went back over the weekend.

  11. This post has been deleted by its author

  12. Mage Silver badge

    Some pulses received

    .... . .-.. .--. -- . .. .- -- - .-. .- .--. .--. . -.. .. -. .- -. . ..- - .-. .. -. --- ..-. .- -.-. - --- .-. -.--

    A 1907 Coherer for Radio probably works better than any detector for Neutrinos

  13. Andy Farley

    Could they not...

    have different spacings between the pulses to correlate them better?

  14. Scott Broukell
    Coat

    "Hello ... CERN help desk.."

    "What?, your neutrino experiment gave some strange results, ...... mmmm ....... have you tried turning it off and then on again ?

  15. Solly
    Joke

    Sorry but we don't serve neutrino's in here.

    A neutrino walks in to a bar.

    1. Scott Broukell
      Pint

      A neutrino goes into a pub ...........

      .... and not a single person notices it.

      Within minutes several billion, squillion other neutrinos go into the same pub.

      Once again nobody notices a thing.

      Then one neutrino lepton to the bar and did a little jig, which may or may not have caught the attention of at least one person in the bar.

      I blame it all on the amount of tau-killer slammers.

      <did i post this twice?>

    2. Scott Broukell
      Pint

      A neutrino went into a bar ........

      ... and not one person noticed.

      75 trillion squillion other neutrinos went into the same bar and still nobody noticed.

      Then one neutrino lepton to the bar and did a little jig, which may or may not have been noticed by at least one or more peeps in the bar, but who can tell?

      I blame it all on those tau-quila slammers.

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